It would depend on why the misjumped. If it was a result of a navigation error then yes, all ships would be using bad data. If it was a result of the ships encountering a large planetary body in the path of their jump then yes, they should all misjump together. If it was the result of a mechanical failure (or using unrefined fuel) or some other error isolated to a single ship, then on, the fleet would proceed as expected and the single ship would misjump on it's own.
